Color screens for diffusion transfer processes containing color formers

ABSTRACT

avoid this defect or hazard. The net effect of this defect or hazard on the completed three color positive image is a deterioration in hue image quality known to the art as &#39;&#39;&#39;&#39;cross talk&#39;&#39;&#39;&#39; or &#39;&#39;&#39;&#39;dye drop-off.&#39;&#39;&#39;&#39; This defect or hazard in subtractive depthwise stacking is usually minimized by a number of secondary techniques outlined in numerous supporting patents (see for example U.S. pat. Nos. 3,230,082; 3,265,498; 3,069,263; 3,208,991; etc.) which may be classified in their collective sense as &#39;&#39;&#39;&#39; Cross Talk Technology.&#39;&#39;&#39;&#39; A subtractive lateral stacking mode in which the color elements yield color or color forming streams which progress in a side-byside or lateral manner out of a two dimensional planar negative towards a receiving sheet or layer would obviate a reaction between any color or color forming stream and a photosensitive element not proper to its modulation and would not exhibit the defect or hazard known as &#39;&#39;&#39;&#39;cross talk&#39;&#39;&#39;&#39; or &#39;&#39;&#39;&#39;dye drop-off&#39;&#39;&#39;&#39; common to diffusion transfer systems based on subtractive depthwise stacking modes. Such lateral modes are thus the natural choice for proper use in color diffusion transfer photography. Such modes have previously been proposed for diffusion transfer color systems (see for example British Pat. No. 926,462) in the form known to the art as &#39;&#39;&#39;&#39;mixed grain screens,&#39;&#39;&#39;&#39; or &#39;&#39;&#39;&#39;photosensitive screens.&#39;&#39;&#39;&#39; In such approaches a two dimensional array is coated, printed, or formed in diverse ways in random or structured patterns as a mixture of a multitude of three classes of micro areas normal to the direction of exposure. The first class consists of silver halide grains sensitive to blue light only and accompanied by a yellow color precursor; the second class consists of silver halid grains sensitive to green light, accompanied by a magneta color precursor and a yellow filter dye; the third class consists of silver halide grains sensitive to red light, accompanied by a cyan color precursor and a yellow filter dye. The exposing actinic radiation is thus analyzed and registered in the three different areas of the photo sensitive screen containing color forming agents proper to its reproduction. In the development step the color precursor reacts with oxidized color developer to form an insoluble dye which remains in the screen; left over color former transfers to a receiving sheet to form a pre-color positive image which upon treatment yields a full color reproduction. Size, proportion, and location of the differential areas may be chosen such that the result duplicates the reproduction available from subtractive depthwise stacking modes. Area overlap upon diffusion removes the pattern of the original screen. This is an unsophisticated and direct approach to the problem of subtractive lateral stacking and amounts in principle to mere r A dual-nature screen process wherein a panchromatic emulsion is exposed through the screen, then brought into intimate contact with a receiving element with a fast acting color developer of pH 10.0 to 11.0 interposed. The color formers from the screen, modulated by the exposed panchromatic emulsion, diffuse to the receiving layer of the receiving element where they are converted to azomethine or indoaniline dyes. The receiving element may be of a nature wherein it is peeled off of the joined configuration for viewing or it may be of the type wherein the finished image may be viewed in the joined configuration. This invention relates to the making of positive color reproductions of faithful to the hue, saturation and density variations fo the original image using a novel stutractive lateral stacking mode. Additive lateral stacking modes are well known to the prior art (see for example U.S. Pat. Nos. 411,186; 471,187; 822,532; 877,351; 1,429,430; etc.) under the generic name of &#39;&#39;&#39;&#39;Screen Plates&#39;&#39;&#39;&#39; and represented the main stream of inventive effort for three color photography before their sudden eclipse following the introduction of practical tripacks to the marketplace. In these schemes, a so called &#39;&#39;&#39;&#39;Screen&#39;&#39;&#39;&#39; was interposed permanently between, on the one hand, a panchromatic emulsion and the screne to be imaged; and, on the other hand in the postreversal-development stage, between the resulting silver image and the observer. The screen thus served a dual purpose; that of color analysis in the imaging stage and color provider in the viewing stage. THE SCREEN WAS COMPOSED OF A MULTITUDE OF RED, GREEN, AND BLUE MICORFILTERS OF SUCH SIZE AND DISTRIBUTION LATERALLY IN A TWO DIMENSIONAL ARRAY AS TO GIVE A TOTAL IMPRESSION OF WHITE LIGHT TO THE EYE AT A GIVEN VIEWING DISTANCE AND PROJECTION MAGNIFICATION BELOW THE RESOLVING POWER OF THE RETINA; YET MAINTAINING THE ABILITY OF THE ADJACENT PANCHROMATIC EMULSION TO RESOLVE SUCH MINUTE AREAS BELOW THE THRESHOLD OF RETINAL RESOLUTION INTO THEIR DIFFERENTIAL COMPONENTS OF RED, GREEN, AND BLUE, ONLY, BY REGISTERING AS LATENT IMAGE RED LIGHT ONLY IN THOSE EMULSION GRAINS COVERED BY RED MICROFILTERS; BLUE LIGHT ONLY IN THOSE EMULSION GRAINS COVERED BY BLUE MIRCROFILTERS; AND GREEN LIGHT ONLY IN THOSE EMULSION GRAINS COVERED BY THE GREEN MICROFILTERS. It will become apparent to the careful reader that the selective blockage of light via reversal development of the panchromatic emulsion to yield a positive silver record of that imaged pattern, viewed through the still intact filter screen will be seen as a reverse analysis of the tricolor imaging and, under the conditions presented, appear as one color sensation to the eye, that color being the color of the original point in the object. Such principles are well known to those versed in the history of the art and are presented here to emphasize the differences between these early additive lateral stacking modes and our novel subtractive lateral stacking modes. The defects inherent in such additive lateral stacking modes are manifold and let to their quick replacement by subtractive depthwise stacking modes known bY the generic name as &#39;&#39;&#39;&#39;tripacks.&#39;&#39;&#39;&#39; For instance, screen systems prove practical for projection purposes only; they discard two thirds of the light in the projection beam and project dimly; further reproduction of the picture proves practically impossible since the new screen would require a point-to-point coincidence with the old screen to avoid moire patterns; since the screen remains for viewing one must accept the superimposition of the screen pattern on the picture, etc. The above gross defects are itemized because of an unfortunate accident of history. Subtractive as opposed to additive lateral stacking modes developed much later have used the nomenclature &#39;&#39;&#39;&#39;screen&#39;&#39;&#39;&#39; - ours included. Such &#39;&#39;&#39;&#39;screens,&#39;&#39;&#39;&#39; to be discussed later, are not to become confused with these old &#39;&#39;&#39;&#39;screen systems&#39;&#39;&#39;&#39; and have none of the defects itemized above, even though at some times in the process they bear what is only a superficial resemblance to these early screens. The tripack utilized reactions of the latent image bearing silver halide to form cyan, magneta, and yellow dye images in different red sensitized, green sensitized, and blue sensitive layers respectively (see for example U.S. Pat. Nos. 1,954,452; 2,010,459; English Pat. No. 481,501; etc.). The imaging, color providing multilayers were stacked, or coated vertically to the direction of imaging or viewing forming a depthwise arrangement of the color elements as opposed to the previous side-by-side or lateral arrangement of color elements in the additive scheme. The color forming reaction of latent images took place with immediately after imaging as in negative-positive systems, or after a second exposure or fogging following black and white development of the image registered latent image as in reversal development. These subtractive depthwise stacking packages obviated all of the above defects of the additive lateral stacking modes and provided the basis for so-called &#39;&#39;&#39;&#39;conventional&#39;&#39;&#39;&#39; color films to this day. Of course additive depthwise color modes never entered the picture since any two primary colors stacked depthwise for viewing yield black. Given the ease with which multilayer subtractive depthwise stacking modes are coated by modern techniques, and given the pleasing results they yield for conventional color photography, no serious efforts have been made to perfect the fourth permutation; namely subtractive lateral stacking modes. It is only with the advent of practical diffusion transfer color photography that the need for subtractive lateral stacking modes become apparent and indeed imperative. Aside from early attempts to utilize the old additive lateral stacking modes described above in a color transfer scheme (see for example U.S. Pat. No. 2,707,150) via the transfer both of positive silver and additive screen to a receiving sheet, the main thrust of diffusion transfer schemes have used the subtractive depthwise stacking modes of more conventional color photography (see for example U.S. Pat. No. 2,983,606). In most of these schemes a dye developer is coated immediately behind a photosensitive layer sensitive to that due of light complementary to the hue of the dye developer. The dye developer solubilizes during processing and passes through the image bearing layer on its way to a receiving sheet or layer. While in the image bearing layer the dye stream is modulated imagewise by reaction between dye developer and latent image to form nondiffusible deposits. The dye stream now continues towards the receiving sheet now bearing a positive dye image record of that primary color. Three such pairs of photosensitive layers and their companion dye developer layers are coated or stacked depthwise in a complete package to yield three color reproductions of the original image on the receiving sheet or layer which has a mordanting ability to hold each of the three modulated dye streaMs which reach it. Analogous schemes involving color formers have also been disclosed (see for example U.S. Pat. No. 3,359,104). The careful observer will note that subtractive depthwise stacking modes while eminently suitable for more conventional three color photography are not directly suitable without extensive modification and painstaking effort for diffusion transfer three color photography. By the very nature of depthwise stacking of color elements, the already properly modulated dye or color former stream of at least some color element must pass through the modulating photosensitive layer of another, noncomplementary, improper color and be subject to the defect or hazard of further, undesirable, improper modulation by another image bearing layer interdicting its path to the receiving sheet or layer; there being no way to stack depthwise elements in three color photography to

United States Patent. r191 Waxman et al.

[ ]*Aug. 12, 1975 COLOR SCREENS FOR DIFFUSION TRANSFER PROCESSES CONTAINING COLOR FORMERS Inventors: Burton Harvey Waxman; Robert Thomas Shannahan, both of Endicott; Felix Viro, Appalachin, all

of NY.

[73] Assignee: GAF Corporation, New York, NY.

[ Notice: The portion of the term of this patent subsequent to Apr. 17, 1990, has been disclaimed.

[22] Filed: Mar. 2, 1973 [21] Appl. No.: 320,644

[52] US. Cl. 96/3; 96/25; 96/29 D; 96/77; 96/80; 96/117; 96/118 [51] Int. Cl. G030 7/00; G030 5/54; G030 7/04; G030 1/40; G030 l/84; G03f 5/00 [58] Field of Search 96/3, 29 D, 77, 80, 25, 96/1 18, 1 17 [56] References Cited UNITED STATES PATENTS 2,968,554 l/l96l Land 96/3 3,301,772 1/1967 Viro 96/3 3,359,104 12/1967 Viro 96/3 3,709,693 l/l973 Bloom et al. 96/3 3,728,1 l6 4/1973 Waxman et al. 96/3 Primary ExaminerNorman G. Torchin Assistant ExaminerRichard I... Schitting Attorney, Agent, or Firm-Walter C. Kehm; James N, Blauvelt [57] ABSTRACT A dual-nature screen process wherein a panchromatic emulsion is exposed through the screen, then brought into intimate contact with a receiving element with a fast acting color developer of pH 10.0 to 11.0 interposed. The color formers from the screen, modulated by the exposed panchromatic emulsion, diffuse to the receiving layer of the receiving element where they are converted to azomethine or indoaniline dyes.

The receiving element may be of a nature wherein it is peeled off of the joined configuration for viewing or it may be of the type wherein the finished image may be viewed in the joined configuration.

8 Claims, 27 Drawing Figures VIEWING PATENTED AUG 1 2 I975 Fla 5 AAAAAAAAA (a) PAIENTEU AUG 1 21975 SHEET 5 VIEWING VIEWING 5 T 5 IMAGING "All r a 0 a a a a Vll/A'IIIIIIifiW/IIIIIIIIVA T VIEWING i IMAGING PATENTEDAUE 1 2197s 3, 9 330 SHEET 6 F IG.

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' PATENTED 2|975 3, 899,330

SHEET 7 (a IMAGING AAAAA F/G. I34

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AAAAAAA l V I E W I N G PATENTEDAUGIZIQYE 3,899,330 sum 9 (E IMAGING Fla/5A H AAAAAAA i VIEWING COLOR SCREENS FOR DIFFUSION TRANSFER PROCESSES CONTAINING COLOR FORMERS This invention relates to the making of positive color reproductions of faithful to the hue, saturation and density variations fo the original image using a novel stutractive lateral stacking mode.

Additive lateral stacking modes are well known to the prior art (see for example US. Pat. Nos. 41 1,186; 471,187; 822,532; 877,351; 1,429,430; etc.) under the generic name of Screen Plates and represented the main stream of inventive effort for three color photography before their sudden eclipse following the introduction of practical tripacks to the marketplace.

In these schemes, a so called Screen was interposed permanently between, on the one hand, a panchromatic emulsion and the serene to be imaged; and, on the other hand in the post-reversal-development stage, between the resulting silver image and the observer. The screen thus served a dual purpose; that of color analysis in the imaging stage and color provider in the viewing stage.

The screen was composed of a multitude of red, green, and blue micorfilters of such size and distribution laterally in a two dimensional array as to give a total impression of white light to the eye at a given viewing distance and projection magnification below the resolving power of the retina; yet maintaining the ability of the adjacent panchromatic emulsion to resolve such minute areas below the threshold of retinal resolution into their differential components of red, green, and blue, only, by registering as latent image red light only in those emulsion grains covered by red microfilters; blue light only in those emulsion grains covered by blue mircrofilters; and green light only in those emulsion grains covered by the green microfilters. It will become apparent to the careful reader that the selective blockage of light via reversal development of the panchromatic emulsion to yield a positive silver record of that imaged pattern, viewed through the still intact filter screen will be seen as a reverse analysis of the tricolor imaging and, under the conditions presented, appear as one color sensation to the eye, that color being the color of the original point in the object.

Such principles are well known to those versed'in the history of the art and are presented here to emphasize 'the differences between these early additive lateral stacking modes and our novel subtractive lateral stacking modes.

The defects inherent in such additive lateral stacking modes are manifold and let to their quick replacement by subtractive depthwise stacking modes known by the generic name as tripacks.

For instance, screen systems prove practical for projection purposes only; they discard two'thirds of the light in the projection beam and project dimly; further reproduction of the picture proves practically impossible since the new screen would require a point-to-point coincidence with the old screen to avoid moire patterns; since the screen remains for viewing one must accept the superimposition of the screen pattern on the picture, etc.

The above gross defects are itemized because of an unfortunate accident of history. Subtractive as opposed to additive lateral stacking modes developed much later have used the nomenclature screen ours included. Such screens, to be discussed later, are not to become confused with these old screen systems and have none of the defects itemized above, even though at some times in the process they bear what is only a superficial resemblance to these early screens.

The tripack utilized reactions of the latent image bearing silver halide to form cyan, magneta, and yellow dye images in different red sensitized, green sensitized, and blue sensitive layers respectively (see for example US. Pat. Nos. 1,954,452; 2,010,459; English Pat. No. 481,501; etc.). The imaging, color providing multilayers were stacked, or coated vertically to the direction of imaging or viewing forming a depthwise arrangement of the color elements as opposed to the previous side-by-side or lateral arrangement of color elements in the additive scheme. The color forming reaction of latent images took place with immediately after imaging as in negative-positive systems, or after a second exposure or fogging following black and white development of the image registered latent image as in reversal development.

These subtractive depthwise stacking packages obviated all of the above defects of the additive lateral stacking modes and provided the basis for so-called conventional color films to this day. Of course additive depthwise color modes never entered the picture since any two primary colors stacked depthwise for viewing yield black.

Given the ease with which multilayer subtractive depthwise stacking modes are coated by modern techniques, and given the pleasing results they yield for conventional color photography, no serious efforts have been made to perfect the fourth permutation; namely subtractive lateral stacking modes. It is only with the advent of practical diffusion transfer color photography that the need for subtractive lateral stacking modes become apparent and indeed imperative.

Aside from early attempts to utilize the old additive lateral stacking modes described above in a color transfer scheme (see for example US. Pat. No. 2,707,150) via the transfer both of positive silver and additive screen to a receiving sheet, the main thrust of diffusion transfer schemes have used the subtractive depthwise stacking modes of more conventional color photography (see for example US. Pat. No. 2,983,606).

In most of these schemes a dye developer is coated immediately behind a photosensitive layer sensitive to that due of light complementary to the hue of the dye developer. The dye developer solubilizes during processing and passes through the image bearing layer on its way to a receiving sheet or layer. While in the image bearing layer the dye stream is modulated imagewise by reaction between dye developer and latent image to form non-diffusible deposits. The dye stream now continues towards the receiving sheet now bearing a positive dye image record of that primary color. Three such pairs of photosensitive layers and their companion dye developer layers are coated or stacked depthwise in a complete package to yield three color reproductions of the original image on the receiving sheet or layer which has a mordanting ability to hold each of the three modulated dye streams which reach it. Analogous schemes involving color formers have also been disclosed (see for example US. Pat. No. 3,359,104).

The careful observer will note that subtractive depthwise stacking modes while eminently suitable for more conventional three color photography are not directly suitable without extensive modification and painstaking effort for diffusion transfer three color photography. By the very nature of depthwise stacking of color elements, the already properly modulated dye or color former stream of at least some color element must pass through the modulating photosensitive layer of another, non-complementary, improper color and be subject to the defect or hazard of further, undesirable, improper modulation by another image bearing layer interdicting its path to the receiving sheet or layer; there being no way to stack depthwise elements in three color photography to avoid this defect or hazard. The net effect of this defect or hazard on the completed three color positive image is a deterioration in hue image quality known to the art as cross talk or dye drop-off. This defect or hazard in subtractive depthwise stacking is usually minimized by a number of secondary techniques outlined in numerous supporting patents (see for example US. pat. Nos. 3,230,082; 3,265,498; 3,069,263; 3,208,991; etc.) which may be classified in their collective sense as Cross Talk Technology.

A subtractive lateral stacking mode in which the color elements yield color or color forming streams which progress in a side-by-side or lateral manner out of a two dimensional planar negative towards a receiving sheet or layer would obviate a reaction between any color or color forming stream and a photosensitive element not proper to its modulation and would not exhibit the defect or hazard known as cross talk or dye drop-off common to diffusion transfer systems based on subtractive depthwise stacking modes. Such lateral modes are thus the natural choice for proper use in color diffusion transfer photography.

Such modes have previously been proposed for diffusion transfer color systems (see for example British Pat. No. 926,462) in the form known to the art as mixed grain screens, or photosensitive screens.

In such approaches a two dimensional array is coated, printed, or formed in diverse ways in random or structured patterns as a mixture of a multitude of three classes of micro areas normal to the direction of exposure. The first class consists of silver halide grains sensitive to blue light only and accompanied by a yellow color precursor; the second class consists of silver halid grains sensitive to green light, accompanied by a magneta color precursor and a yellow filter dye; the third class consists of silver halide grains sensitive to red light, accompanied by a cyan color precursor and a yellow filter dye.

The exposing actinic radiation is thus analyzed and registered in the three different areas of the photo sensitive screen containing color forming agents proper to its reproduction. In the development step the color precursor reacts with oxidized color developer to form an insoluble dye which remains in the screen; left over color former transfers to a receiving sheet to form a pre-color positive image which upon treatment yields a full color reproduction.

Size, proportion, and location of the differential areas may be chosen such that the result duplicates the reproduction available from subtractive depthwise stacking modes. Area overlap upon diffusion removes the pattern of the original screen.

This is an unsophisticated and direct approach to the problem of subtractive lateral stacking and amounts in principle to mere re-arrangement of depthwise stacking modes to force a more desirable lateral stacking mode. Though it was a convenience of the subtractive depthwise stacking modes that color analysis could be achieved by the use of three differing classes of silver halide grains, it proves a weighty disadvantage to keep that feature in a subtractive lateral stacking mode when it is not needed, when indeed experiences with additive lateral stacking modes teach that a further advantage of lateral modes is simplicity of color analysis; that is to say, latent image may be color separated in a two dimensional array successfully by using a three color microfilter array over a single emulsion of panchromatic silver halide grains. If that three color microfilter array coexists with an array of three color formers such that micro areas containing blue filter contain also yellow color former; that micro areas containing red filter contain also cyan color former; and that micro areas containing green filter containing also magneta color former, then a simple and novel lateral mode may be realized for use with diffusion transfer color photography.

In a classical additive lateral stacking mode, the two dimensional microfilter array known as a screen serves a dual purpose; that of color analysis of the actinic light from the scene passing through it to provide laterally distributed single color bits of latent image in the panchromatic emulsion which are reversally developed into silver density image bits for projection; and that of color provider to reproduce the original scene in full color when this black and white density information is projected back through the still intact imaging screen.

In our subtractive lateral stacking mode porposed above the screen also serves a dual purpose; but whereas the classical screen had a single nature which served two purposes and is always kept intact (leading to the gross defects outlined for such systems) our screen has a dual nature, one for each role as color analyzer and color provider, and plays only an intermediate role in providing color, the screen in both its physical natures being discarded after used from the full color reproduction (thus said reproduction has none of the gross defects ordinarily and historically associated with screen schemes). 3

In its first nature our screen is a two dimensional array of red, blue, and green microfilters and serves only in the imaging role for color analysis of actinic light from the scene passing through it to provide laterally distributed single color bits of latent image in the panchromatic emulsion below. Thus it behaves like a classical additive screen, although unlike that screen it plays not further role and is absent from the final reproduction.

Serving the role of color provider and co-existing with the microfilter screen is an array of colorless subtractive color forming diffusible color formers (hereafter referred to as color former(s)); that is to say, microareas containing yellow color former; microareas containing cyan color former; microacreas containing magneta color former.

As essential primary condition for the proper operation of such dual nature screens is that they not only coexist but co-incide in the following manner; that the microareas containing blue dyes be exactly those containing yellow color former; that the microareas containing green dyes be exactly those containing magneta color former; that the microareas containing red dyes be exactly those containing cyan color former. When this condition is met, latent image bits in the panchromatic emulsion below will modulate color former only of a color producing ability complementary to that producing the latent image bit.

Though any one way of constructing such screens or of producing such modulation by latent image bits does not serve as a sole condition or form for operability of our invention, this universal prime condition concerning coincidence of the co-existing arrays is an essential feature of our invention in any embodiment. A secondary universal condition is that any filter dyes employed be non-diffusing in the developing environment since they must play no role in the color forming step.

The. use of such a screen as detailed in our invention is as follows:

1. The color analysis step: The panchromatic emulsion is imaged through the red, blue, and green microfilter array.

2. The color providing step: The screen and panchromatic emulsion are imbibed with a fast acting color developer at a pH from 10.0 to 1 1.0 and simultaneously placed in contact with a receiving layer or sheet such that diffusing color former must pass from the two dimensional array of color former in the screen through the emulsion towards the receiving sheet or layer. The

color formers employed in our invention, in contrast with those of our co-pending application Ser. No. 153,186 filed June 15, 1971, DN-306, now U.S. Pat. No. 3,728,116, issued April 17, 1973, (a difference to be detailed below), are soluble and diffusible in an aqueous gelatine matrix in this pH range, thought not at coating pH values. The action of the developer on the latent image bits provides oxidized color developer in those light struck micro areas of the emulsion.

Simultaneous with this production of oxidized color developer, the cyan color former from the multitude of red microfilter areas will pass through emulsion microareas subtending the red screen areas immediately to their front, said emulsion microareas containging oxidized color develpper in proportion to the amount of red light having impinged upon them. Color former will react with such oxidized developer to form insoluble azomethine or indoaniline dye, not to provide color as in conventional color processes, but to remove or modulate cyan color former from further diffusion in proportion to the intensity of light in the red actinic radiation at that point or microarea causing the latent image bit. The net effect is to turn the diffusing two dimensional array of diffusing color former into a diffusing modulated two dimensional array of color former containing information on the point to point red density variations reproducing the red values of the original scene. This diffusing array continues to the receiving layer or sheet where it is mordanted against further diffusing. An identical development/diffusion mechanism between magneta color former and green latent image bits transfer a modulated magneta color former array to the receiving sheet or layer; and by yet another simultaneously acting, identical development/diffusion mechanism between yellow color former and blue latent image bits, a modulated yellow color former array is transferred to the receiving sheet or layer.

The composite color former image is then brought to full color by inclusion of oxidizing agent within the receiving element to act with excess color developer, or by post transfer treatment of said element with oxidizing agent and a p-phenylene diamine derivative or by any other method proper to the formation of azomethine or indoaniline dyes from the color former precursors.

The color formers of our co-pending application Ser. No. 153,186 were soluble in high boiling solvents, nondiffusing in the aqueous gelatin matrix at pH values encountered in coating and actuated for solution in and diffusion through the aqueous gelatin matrix by pH values greater than 12.5. Such color formers as defined in our co-pending application Ser. No. 153,186, would not function in the development/diffusion mechanism described above for our present invention.

The development/diffusion one step mechanism of our co-pending application Ser. No. 153,186 was actuated by a fast acting color developer of above pH 12.5.

With the advent of debris free color diffusion transfer systems whereby the negative and receiving element are kept permanently in juxtaposition to present a unitary package for viewing (such systems, early proposed by Rogers in U.S. Pat. No. 2,983,606, are the subject of several recent disclosures; see, for example, U.S. Pat. Nos. 3,615,421; 3,635,707; etc.) a shortstopping feature lowering the residual pH of the enclosed developer is needed for stability.

Such systems are best developed by a fast acting developer in accordance with the present invention, affording a reasonable capacity for short-stopping, such as one operating in the pH range from 10.0 to 1 1.0.

Said fast acting color developer in this desired pH range has been formulated by the inventors to be detailed later in the application, its rapidity of action being probably due to the synergistic behavior of trace additions of auxiliary developers.

A measure of its rapid developing action is to be had by comparing the development rate of this special developer on GAF Color Paper as compared to more conventional developer formulations. ln ordinary processing, exposed GAF Color Paper is brought to full three color development in 8-12 minutes at F. The above mentioned special developer accomplishes this without fogging within one minute at 75. (Note that GAF Color Paper; is a subtractive depthwise stacked color photosensitive package sold by the GAP Corporation, while the planned use of this fast acting developer is with one single panchromatic emulsion, not at all with the at least three sensitive emulsion layers present in GAF Color Paper; indicating even faster development action in its intended use.)

The use of such a developer in our dual action screen development/diffusion one step mechanism calls for companion color formers rapidly diffusible into the panchromatic emulsion layer at pH values from 10.0 to l 1.0.

The color formers defined in our co-pending application Ser. No. 153,186 do not diffuse at all in that pH range and are not therefore suitable.

We have discovered, quite to our great surprise, that many conventional low molecular weight color formers known to the art as non-incorporated couplers," and normally present in developer solutions but never present in photosensitive elements, are soluble in high boiling solvents, fast towards diffusion through an aqueous gelatine matrix at pH ranges employed in coatings (making these color formers on both counts proper to our screen making techniques to be described below), but which become soluble, rapidly diffusible, and reactive with oxidized p-phenylene diamine derivatives at pH values in the 10.0 to 1 1.0 pH range.

Examples of such couplers with the preceeding attributes include the three below available from the Eastman Kodak Company under the designation C-lO, M-38, and Y-54 respectively.

I. A cyan color former: N (a-acetamid'o phenethyl) l hydroxy 2 napthamide II. A magenta color former: l (2,4,6 trichlorophenyl) 3 p nitroanilino 2 pyrazolin-S one III. A yellow color former: c benzoyl 0 methoxy acetanilide These are especially effective in a development/diffusion mechanism with a developer as below.

IV. Fast acting color developer, pH 10.6:

(amounts are per liter of developer) Z-nmino-S-dicthylaminololucnc hydrochloride. *Alipal (O-436 is a polyethylene Oxidc Surfactant sold by the GAF Corporation.

Many methods for making a dual nature screen for the above described process would become apparent to those steeped in a knowledge of the history of the art as analogous methods to those used in making classical screen plates as outlined in The History of Color Photography by J. S. Friedman; namely photographic printing, block methods, photomechanical printing, ruled lines, resists, etc.

We have, however, chosen for the preferred way of forming our dual screen the facile, inexpensive, novel method outlined on our co-pending application Ser. No. 153.186 yielding the so-called oil droplet screen analogous to the one described therein.

The combination of a so made dual nature screen, encompassing the prime and secondary formation conditions mentioned before, incorporated therein these previously so called non-incorporated couplers" as exemplified by I, II, and III in juxtaposition with a panchromatic emulsion given a post exposure treatment with a fast acting developer of pH range 10.0 to l 1.0, exemplified by IV, to transfer by one simultaneous development/diffusion mechanism a composite modulated color former reproduction of the original scene to be converted to full colored azomethine and/or indoaniline dyes, the screen playing no role in the image viewing thereafter, comprises the object of this invention.

The object, realization, and embodiments of this invention are to be best understood by reference to the following figures:

FIGS. 1A through D schematically represent the mixing of the screen coating solution;

FIGS. 2A through D show the coating, imaging, and processing configurations of a dual screen photosensitive system;

FIGS. 3A through C show an over head view of an area of the dual screen pointing out its dual nature and the primary condition coupling the two natures;

FIGS. 4A through E show a simplified three dimensional view of the color analysis and color provider actions of an oil droplet dual screen showing the action of only two droplets for clarity;

FIG. 5 shows the simplest screen package;

FIG. 6 shows a laboratory device for processing the package shown in FIG. 5;

FIG. 7 shows a schematic representation of a bulk processing procedure for large amounts of screen film as would be the case, for example, in its embodiment as a quick access movie film;

FIGS. 8 through 12 show peel apart embodiments of our invention and their imaging and viewing configuration; and

FIGS. 13 through 15 show various debris free embodiments of our invention and their imaging and viewing configuration.

The secondary condition concerning the nondiffusion of the filter dyes is met by employing single or mixed primary color dyes, or mixed subtractive dyes whose combined absorption approximates a primary color, which are soluble in high boiling organic solvents (here after referred to as oil), and neither soluble nor diffusible in an aqueous gelatin matrix at any pH value. It is preferable, though not necessary, to use mixed primary dyes as opposed to single primary dyes so as to enhance the oil solubility of each.

Among the examples of such dyes or dye mixtures are the following:

V. Red Filter Dye: A 1:1 mixture of Sudan Red GGA and Sudan Red BBA.

VI. Blue Filter Dye: A 1:1 mixture of Sudan Blue CSP and Methyl Violet Base.

VII. Green Filter Dye: A 1:1 mixture of the below subtractive dyes:

I o H II H H l I H H C-N-(CH -N-C C-C-C-N 1 C 5 N N(CH CH cH '3 N (cm H (t H s 2.

CYAN term In general the procedure for forming an oil droplet screen is begun by making three separate oil in water dispersions as follows. A primary filter dye is dissolved along with a color former of the color producing ability complementary to that primary color in oil. That oil mixture is then dispersed in an aqueous gelatin medium as schematically shown in FIG. 1 in the form of oil droplets of 5 to 20 microns diameter. FIGS. 1A, 1B, and 1C show the green, red-and blue screen dispersions respectively.

The following three dispersion formulations are among the examples of those functioning towards the proper operation of our invention:

VIII. A green screen dispersion:

Oil Phase: Dissolve 1.0 gram of green filter dye VII 1.0 gram of magneta color former ll 2.0 c.c. dibutylphthalate 2.0 c.c. Santicizer 160* with heating. Aqueous Phase; 45 c.c. of 8% gel solution with 6.0 c.c of Alkanol B**.

*Butyl Bcnlyl Phthalate available from the Monsanto Company "Sodium alkyl naphthalene sulfonate available from E. I. DuPont dc Ncmours and Co. made into a 10% aqueous solution.

Then disperse with gentle mechanical stirring for 100 seconds the hot oil into the aqueous phase at 50C.

IX. A red screen dispersion:

Aqueous Phase:

Then disperse with gentle mechanical stirring for 100 seconds the hot oil into the aqueous phase at 50C.

X. A blue screen dispersion:

1.0 gram of blue filter 1.0 gram of yellow color formers III 2.0 c.c. dibutylphthalate 2.0 c.c. Santicizcr 160 Oil Phase; Dissolve with heating.

45 c.c. of 8% gel 6.0 c.c. of Alkanol B Aqueous Phase Then disperse with gentle mechanical stirring for 100 seconds the hot oil into the aqueous phase at 50C.

To form the screen coating solution, FIG. 1D, the dispersions represented by FIGS. 1A, 1B and ID are melted and mixed in desired proportions. These proportions vary with intended usage. They may be a simple l to l to 1 equal ratio each color, or one or the other color may be in greater proportion in the mixture in order to, for example, balance the spectral response of the panchromatic emulsion with the quality of the actinic radiation to produce a net neutral gray scale, a procedure known to the art as color balancing; a procedure normally achieved by emulsion and sensitizing dye choice in the art; but which may in our invention, be at least partially achieved for a panchromatic emulsion by the mixing ratio of color screen components in making up the screen coating solution.

The screen may now be coated as shown in FIG. 2A where 1 represents transparent subbed film base and 2 represents the still wet screen layer.

Upon drying the round oil droplets undergo a lateral stress and respond by flattening out horizontally to form flat spheroids,.expanding to fill the space between them laterally as shown in layer 2, FIG. 2B to form the tightly packed mosaic shown in FIG. 3A, which represents a screen segment as viewed from above (the dried gelatin binder in between is exaggerated for reasons of clarity).

From the method of forming the coating solution, the careful reader can ascertain that the mosaic in FIG. 3A is of a dual nature as represented by FIGS. 38 and 3C and that the microareas containing a given filter dye will be exactly those containing the color former of a color producing ability complementary to the color of the filter dye. Thus the prime condition of screen formation is fulfilled automatically.

The screen is usually coated to a wet thickness of from 50 to microns; but especially to that thickness which upon drying will form the tight packed mosaic of FIG. 3A without the formation of over lap; that is to say a condition where a significant number of droplets form a second stratum whereby two droplets of differing color values subtend the same microarea, another way in whichthe prime condition is violated.

Though routine calculations on droplet population, wet thickness, and area to be covered can yield proper wet thickness ranges allowable, trial and error coating readily zero in on the proper coating conditions.

Once the dual screen layer is properly laid down as an optimum mosaic, a panchromatic emulsion layer (layer 3, FIG. 2C) is coated over the screen.

The panchromatic emulsion is coated to a coating weight of from 1 to 3 grams per square meter of silver but especially to that coating weight which provides for the stopping or reaction with all color former passing through regions of maximum exposure and coming from the mosaic screen in layer 2. Once more, while routine calculations involving the stoichiometry of silver induced color coupling can estimate this amount, it is also readily found in a short series of trial and error experiments.

The base and two coated layers shown in FIG. 3C represent the minimum negative element necessary and sufficient for the operation of ourinvention. Imaging takes place through the base as shown in FIG. 3C.

The' development/diffusion mechanism described heretofor is actuated by interposing (in position 4 of layer ZDl-s in this instance, a developer solution of the type given by IV, with the addition of a viscosity providing substance if desired, between layer 3 and a receiving element among those to be catalogued later.

As layer 2 swells, the lateral strain producing the flattened out droplets is relieved and they recoil subtending a microarea of the screen from which color formers emerge which are smaller, but within the limits of, the microarea recording the primary color information on the latent image. This produces a latent image target u for the color former to stream through on its way to the receiving layer wider than the width of the stream itself assuring proper and complete interaction.

The recording and transfer steps carrying out the intention of the development/diffusion mechanism described heretofore are best understood by reference to FIGS. 4A and 4B which show three dimensional views of the process described A leaving out all other details of the screen for clarity except for two representational oil droplets). The principles taught in the preceeding portions of our specification can be graphically seen in these views.

The simplest, though not the only embodiment of our invention can be seen in FIG. where the simplest receiving element B, (where 7 is an opaque white reflecting base such as Printon, available from the GAF Corporation) and the simplest negative element A are shown.

The element A, exposed as in FIG. 2C, may be processed in a simple laboratory machine shown in FIG. 6 wherein each element winds up in a face to face juxtaposition with developer in between as in FIG. 2D. After 1-3. minutes B is peeled off and treated in an oxidizing agent such that the residual developer and transferred color formers react to form a full color reproduction of the original scene.

The embodiment in FIG. 5 is deceptively simple and has implications beyond its use as a laboratory screening method.

By including aromatic or heterocyclic azides in layer 5, it becomes the base for a one solution bulk processor as shown'in FIG. 7 where rollers a, b, and c guide long lengths of exposed A and receiving element B together with developer interposed, peel them apart again and pass B past an ultra-violet source -d where. full color azomethine dyes are produced from residual developer and transferred color former by the method of Sagura and Van Allan (see U.S. Pat. No. 3,062,650).

If 7 is changed to'a transparent base, then this simple embodiment processed as in FIG. 7 becomes the basis for an inexpensive quick access movie film.

Other embodiments of our invention embracing peel apart instant access camera films are shown in FIGS. 8 through 12 which picture several alternative ways of obtaining lateral reversal of the image for proper viewing and the individual layer arrangements for carrying each out. In these figures, A represents the negative element, B represents the matching element to be married to A during development and C represents the final viewing element.

The numbered layer arrangements have the following meaning:

Layer 1 is a transparent film base, such as polyester cellulose acetate, cellulose acetate butyrate, and the like, with a thickness of 2.59.0 mils.

Layer 2 is the three color dual screen coated from the principles heretofore disclosed.

Layer 3 is the panchromatic emulsion coated from the principles heretofore disclosed.

Layer 4 is the pod containing a fast acting color developer operating in the pH to l 1 region such as disclosed in formulation IV plus a thickening agent such as methyl cellulose to aid in forming a uniform film of developer between A and B.

Layer 5 is the image receiving layer which may for example be composed of acid treated gelatin of 5-10 microns thickness.

Layer 6 is the encapsulated oxidizer and neutralizer layer, of conventional materials, 2-4 microns thick. j;

Layer 7 is a transparent base or overlay which becomes the protective layer or covering on the positive print after separation. A

Layer 8 is a reflective cardboard or reflective pa, base stock. In the case of FIGS. 8 and 9, it is a cardboard mount added to the B element after processing in such a manner that the image to be viewed has the same lateral symmetry as the original object. In the case of FIG. 10, it represents the flexible double weight paper base on which element B is originally coated.

Layer 9- is an alkali stripping layer 2-4 microns in thickness.

Layer l0 is a contact stripping sheet and may be any flexible composition or film base which has one side treated so as to cause permanent adhesion between it and the screen layer 2 when developer is spread between said layers. This allows, after the required diffusion time to strip off in coaction with Layer 9, Layers 2 and 3 in FIG. 9, to reveal the color image in Layer 5 which is then married to cardboard 8 to form the viewing element C.

Layer 1 1 is a white opaque pigment layer containing T O or the like.

The A element in FIG. 8 is imaged as indicated; then developer from the pod 4 is interposed between imaged A and receiving element B which is brought into intimate contact. After 13 minutes, B is peeled off and married to cardboard 8 in the indicated manner, the image being viewed in the direction of the arrow.

The A element in FIG. 9 is imaged as indicated; then developer from the pod 4 is interposed between imaged A and stripping element B which is brought into intimate contact. After 1-3 minutes, the image is prepared for viewing as previously disclosed in the actions of Layer 10.

The A element in FIG. 10 is imaged as indicated; then developer from the pod 4 is interposed between imaged A and receiving element B which is broughtinto intimate contact. After 1-3 minutes B is peeled off for immediate viewing in the direction of the arrow.

FIG. 11 represents a permutation of FIG. 8 where in the position of Layers 2 and 3 are reversed involving a change in viewing and imaging directions. The processing steps are identical. The final image is immediate upon peeling and is viewed through the transparent film base 7 against the reflective layer 11. The element B may optionally be reinforced with a cardboard back- FIG. 12 is a similar permutation of FIG. 9, both permutations being instructive to the careful reader of the necessity of maintaining the proper lateral symmetry requirements of the original object, thus avoiding a mirror image reproduction.

Still other embodiments of our invention, embodiments embracing the so called debris free" systems, are shown in FIGS. 13A, 13B, 14A, 14B, 15A and 158 wherein the A figures show the configurations of the film package before imaging and the B figures show the pod coated additional layers after processing.

Numbered layers are as in previous figures with the following additions:

Layer l2 is a transparent film base identical in nature and composition to 1.

Layer l3 is a carbon black layer whose function during imaging is as an antihalation layer and during viewing is as a back stop for the reflective TiO layer blotting out the negative image beneath.

Layer l4 forms a reflective TiO layer in the B figures and is present as a liquid composition of developer plus TiO in the pod depicted in the A figures.

Layer l5 forms a carbon black' light seal layer in the B figures and is present as a liquid composition of developer plus carbon black in the pod depicted in the A figures.

Layer l6 is a carbon black light seal layer in the B figures and is present as a liquid carbon black suspension in the pod depicted in the A figures.

Layer 17 is a flexible double weight paper base.

Layer 18 is a gelatin layer whose function is to take up the water in the formation of 16.

These embodiments are identical in principle of operation and processing to the embodiments in FIGS. 8 through 12 except in that they are designed specifically to remain as integral packages after processing. In addition the embodiments in FIGS. 14 and are designed to form light seals upon processing in such a manner that they may be processed outside the camera.

In FIG. 13 it is shown that a pod composition in addition to its function of actuating the development/diffusion mechanism may simultaneously coat another layer onto the configuration; in this case a TiO reflection layer.

In FIG. 14 the TiO layer is present (11), and the pod action provides a new carbon black light seal layer.

In FIG. 15 the option is pictured where in both a carbon black light seal layer and a T102 reflective layer are camera coated simultaneously with the actuation of the development/diffusion mechanism disclosed heretofore.

Other options will become apparent to those skilled in the art from these teachings.

EXAMPLE 1 A screen coating solution is formulated from equal amounts of green dispersion VIII, red dispersion IX,

and blue dispersion X. Up to twice the weight equivalence of the oil phase is added to the aqueous gelatin phase in order to prepare each of the dispersions, VIII, IX, X respectively. However it is preferred that a proportion up to l to 1 weight equivalents of hot oilto gelatin be used and the aqueous gelatin is maintained at 40 to 60C. A three color mixed screen is formed therefrom on a transparent polyester film base using the principles disclosed.

This is then over coated with a pan sensitized bromoi- Inspection of the receiving element' through the transparent film base after persulfate treatment shown a color image of the target patches against a white reflective background.

The above examples and disclosure are meant to teach the practice of the invention and are not meant to restrict the scope of the invention to these disclosures and examples. To illustrate, the apparatus and method of E. H. Land, US. Pat. No. 3,032,008 granted May 1, 1962 may be used to provide a geometric patterned dual nature screen in accordance with the present invention.

What is claimed is:

l. A two dimensional dual nature screen of from one to three colors, comprising an array of red, green or blue colored oil droplets, each droplet containing a non-diffusing filter dye having one of the primary colors in addition to a low molecular weight colorless color former fast to diffusion in aqueous gelatin matrices having a pH normal to photographic coating operations of from 6.0 to 7.0 but diffusible through such aqueous gelatin matrices at a pH higher than 7.0, and capable of forming upon coupling with the oxidation products of a paraphenylenediamine color developer a non-diffusing dye complementary in color to the filter dye of the oil droplet in which said color former was contained.

2. The screen according to claim 1, wherein said array of oil droplets is carried by a panchromatic silver halide emulsion.

3. The screen carried by a panchromatic silver halide emulsion, according to claim 2, wherein said oil droplets are of at least two colors selected from the group consisting of red, green and blue.

4. The screen carried by a panchromatic silver halide emulsion, according to claim 3, wherein said colorless color formers are diffusible at a pH of 10.0 to l 1.0.

odo emulsion to'form the negative element shown in FIG. 5.

The receiving element shown in FIG. 5 is obtained by coating a layer of acid treated gelatin 10 microns thick on Printon base which is a TiO impregnated reflective film base available from the GAP Corporation.

A target consisting of red, blue, green, cyan, magenta, and yellow patches is imaged onto the panchromatic emulsion through the screen.

The negative element is then married to the receiving element with developer IV interposed as shown in FIG. 6. After l3 minutes the receiving element is 'peeled off and immersed, still wet with developer, in a 2% aqueous solution of potassium persulfate. Inspection of the receiving sheet shows a full color reproduction of the target patches.

EXAMPLE 5. A method of forming a multicolor reproduction of an original image or object using the dual nature screen carried by a panchromatic emulsion, according to claim 3, comprising:

exposing the panchromatic emulsion through said dual nature screen;

developing said exposed panchromatic emulsion with a fast acting color developer of alkaline pH while said exposed panchromatic emulsion is in contact with a receiving element, said colorless colorformer being diffusible at the pH of said color developer;

allowing sufficient time for maximum color former to transfer through unexposed areas of the panchromatic emulsion and for the cting developer to penetrate and fill the screen panchromatic emulsion and receiving element to actuate the diffusion of the color formers, as modulated by the exposed panchromatic emulsion, from the dual nature screen to the receiving element;

and forming indoaniline or azomethine dyes in the receiving layer from the color former transferred'to the receiving layer by coupling said color former with residual color developer or a p-phenylene derivative in the presence of an oxidizing agent.

6. The method according to claim 5 wherein the 5eceiving element is separated from the panchromatic emulsion and screen for viewing.

7. The method according to claim 5, wherein said fast acting color developer has a pH of 10.0 to l 1.0 and said 1 5 i 1 6 colorless color formers are diffusible at the pH of said a panchromatic silver halide emulsion on said color developer. screen; and

8. A photographic element, comprising, in order: d. a white opaque receiving layer over said emulsion; 2L a transparent film base; the image formed after exposure and development thfl Screen of Claim 1 n Said b21861; being viewed through said transparent film base against said white opaque reflective layer. 

1. A TWO DIMENSIONAL DUAL NATURE SCREEN OF FROM ONE TO THREE COLORS, COMPRISING AN ARRAY OF RED, GREEN OR BLUE COLORED OIL DROPLETS, EACH DROPLET CONTAINING A NON-DIFFUSING FILTER DYE HAVING ONE OF THE PRIMARY COLORS IN ADDITION TO A LOW MOLECULAR WEIGHT COLORLESS COLOR FORMER FAST TO DIFFUSION IN AQUEOUS GELATIN MATRICES HAVING A PH NORMAL TO PHOTOGRAPHIC COATING OPERATIONS OF FROM 6.0 TO 7.0 BUT DIFFUSIBLE THROUGH SUCH AQUEOUS GELATIN MATRICES AT A PH HIGHER THAN 7.0, AND CAPABLE OF FORMING UPON COUPLING WITH THE OXIDATION PRODUCTS OF A PARAPHENYLENEDIAMINE COLOR DEVELOPER A NON-DIFFUSING DYE COMPLEMENTARY IN COLOR TO THE FILTER DYE OF THE OIL DROPLET IN WHICH SAID COLOR FORMER WAS CONTAINED.
 2. The screen according to claim 1, wherein said array of oil droplets is carried by a panchromatic silver halide emulsion.
 3. The screen carried by a panchromatic silver halide emulsion, according to claim 2, wherein said oil droplets are of at least two colors selected from the group consisting of red, green and blue.
 3. A METHOD OF FORMING A MULTICOLOR REPRODUCTION OF AN ORIGINAL IMAGE OR OBJECT USING THE DUAL NATURE SCREEN CARRIED BY A PANCHROMATIC EMULSION, ACCORDING TO CLAIM 3, COMPRISING: EXPOSING THE PANCHROMATIC EMULSION THROUGH SAID DUAL NATURE SCREEN, DEVELOPING SAID EXPOSED PANCHROMATIC EMULSION WITH A FAST ACTING COLOR DEVELOPER OF ALKALINE PH WHILE SAID EXPOSED PANCHROMATIC EMULSION IS IN CONTACT WITH A RECEIVING ELEMENT, SAID COLORLESS COLORFORMER BEING DIFFUSIBLE AT THE PH OF SAID COLOR DEVELOPER ALLOWING SUFFICIENT TIME FOR MAXIMUM COLOR FORMER TO TRANSFER THROUGH UNEXPOSED AREAS OF THE PANCHROMATIC EMULSION AND FOR THE FAST ACTING DEVELOPER TO PENETRATE AND FILL THE SCREEN, PANCHROMATIC EMULSION AND RECEIVING ELEMENT TO ACTUATE THE DIFFUSION OF THE COLOR FORMERS, AS MODULATED BY THE EXPOSED PANCHROMATIC EMULSION, FROM THE DUAL NATURE SCREEN TO THE RECEIVING ELEMENT, AND FORMING INDOANILINE OR AZOMETINE DYES IN THE RECEIVING LAYER FROM THE COLOR FORMER TRANSFERRED TO THE RECEIVING LAYER BY COUPLING SAID COLOR FORMER WITH RESIDUAL COLOR DEVELOPER OR A P-PHENYLENE DERIVATIVE IN THE PRESENCE OF AN OXIDIZING AGENT.
 4. The screen carried by a panchromatic silver halide emulsion, according to claim 3, wherein said colorless color formers are diffusible at a pH of 10.0 to 11.0.
 6. The method according to claim 5 wherein the receiving element is separated from the panchromatic emulsion and screen for viewing.
 7. The method according to claim 5, wherein said fast acting color developer has a pH of 10.0 to 11.0 and said colorless color formers are diffusible at the pH of said color developer.
 8. A photographic element, comprising, in order: a. a transparent film base; b. the screen of claim 1 on said base; c. a panchromatic silver halide emulsion on said screen; and d. a white opaque receiving layer over said emulsion; the image formed after expOsure and development being viewed through said transparent film base against said white opaque reflective layer. 